This invention relates to sound-reproducing devices, to phonographs, and to a simplified phonograph wherein the vibrations of a stylus tracking a spiral groove on a rotating record disc are directly reproduced by a diaphragm as audible vibrations of the air. The simplified phonograph according to the invention finds typical use as a toy or in conjunction with various toys.
In conventional phonographs of the type and class now under consideration, an intermediate vibrator member is arranged between a conical diaphragm and a pivotal tone arm carrying a reproducing stylus. A turntable for placing a record disc thereon is mounted on the inside of an openable lid at the bottom of the phonograph casing. Thus, upon closure of the lid, the stylus will ride in the groove on the record disc on the turntable, with the consequent exertion of pressure on the diaphragm from the turntable via the record, stylus, tone arm, and intermediate vibrator member.
In the foregoing prior art configuration the relative placement of the diaphragm, intermediate member, tone arm, stylus, turntable and so forth must be so precise that the service lives of the diaphragm, stylus and record, in particular, will not be unduly shortened through application of excessive pressure. However, in the phonographs of this class, such precise relative placement of the listed members is both difficult and impractical in view of the costs involved and of the materials in use.
Special attention should be paid to the diaphragm, which easily suffers strain, and hence causes deterioration in the quality of the sound reproduced, when subjected to any undue stress from the intermediate member in contact therewith. It is nevertheless essential for sound reproduction with sufficient volume that the intermediate member be held in contact with the diaphragm under proper pressure. In view of such conflicting requirements the diaphragm has heretofore been resiliently mounted by use of springs, but even then the diaphragm is bound to deform when subjected to forces which cannot be absorbed by the springs.
The prior art phonographs have a further drawback in that the sound reproduced thereby tends to be unnecessarily high-pitched This drawback, as has now been discovered, is a direct result of the resilient mounting of the diaphragm. It has also been found that the structural complexity of the prior art phonographs is a cause of various trouble including the production of poor quality sound through improper vibration of the diaphragm.